linux-kernel - [PATCH] rcu: Replace rcu_dereference() with rcu_access

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Message-ID: <20140816201253.GA18580@ada>
Date:	Sat, 16 Aug 2014 23:12:53 +0300
From:	Andreea-Cristina Bernat <bernat.ada@...il.com>
To:	davem@...emloft.net, mchan@...adcom.com, eddie.wai@...adcom.com,
	peterz@...radead.org, joe@...ches.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc:	paulmck@...ux.vnet.ibm.com
Subject: [PATCH] rcu: Replace rcu_dereference() with rcu_access_pointer()

The "rcu_dereference()" calls are used directly in conditions.
Since their return values are never dereferenced it is recommended to use
"rcu_access_pointer()" instead of "rcu_dereference()".
Therefore, this patch makes the replacements.

The following Coccinelle semantic patch was used:
@@
@@

(
 if(
 (<+...
- rcu_dereference
+ rcu_access_pointer
  (...)
  ...+>)) {...}
|
 while(
 (<+...
- rcu_dereference
+ rcu_access_pointer
  (...)
  ...+>)) {...}
)

Signed-off-by: Andreea-Cristina Bernat <bernat.ada@...il.com>
---
 drivers/net/ethernet/broadcom/cnic.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/cnic.c b/drivers/net/ethernet/broadcom/cnic.c
index 8244e2b..dad9cb7 100644
--- a/drivers/net/ethernet/broadcom/cnic.c
+++ b/drivers/net/ethernet/broadcom/cnic.c
@@ -381,7 +381,7 @@ static int cnic_iscsi_nl_msg_recv(struct cnic_dev *dev, u32 msg_type,
 			break;
 
 		rcu_read_lock();
-		if (!rcu_dereference(cp->ulp_ops[CNIC_ULP_L4])) {
+		if (!rcu_access_pointer(cp->ulp_ops[CNIC_ULP_L4])) {
 			rc = -ENODEV;
 			rcu_read_unlock();
 			break;
@@ -525,7 +525,7 @@ int cnic_unregister_driver(int ulp_type)
 	list_for_each_entry(dev, &cnic_dev_list, list) {
 		struct cnic_local *cp = dev->cnic_priv;
 
-		if (rcu_dereference(cp->ulp_ops[ulp_type])) {
+		if (rcu_access_pointer(cp->ulp_ops[ulp_type])) {
 			pr_err("%s: Type %d still has devices registered\n",
 			       __func__, ulp_type);
 			read_unlock(&cnic_dev_lock);
@@ -573,7 +573,7 @@ static int cnic_register_device(struct cnic_dev *dev, int ulp_type,
 		mutex_unlock(&cnic_lock);
 		return -EAGAIN;
 	}
-	if (rcu_dereference(cp->ulp_ops[ulp_type])) {
+	if (rcu_access_pointer(cp->ulp_ops[ulp_type])) {
 		pr_err("%s: Type %d has already been registered to this device\n",
 		       __func__, ulp_type);
 		mutex_unlock(&cnic_lock);
-- 
1.9.1

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